- Introduction
- Can you detect a pregnancy at 1 week?
- Accuracy
- How accurate are home pregnancy tests?
- False-Positive Results
- What can cause a false-positive pregnancy test result?
- Additional Tests
- What tests are done to confirm pregnancy?
- Complications
- When should you see a doctor?
- FAQs
- Frequently asked questions (FAQs) about pregnancy tests
Can you detect a pregnancy at 1 week?
A home pregnancy test detects the presence of human chorionic gonadotropin (hCG), which is produced in a pregnant woman.
How soon will a pregnancy test read positive? An early pregnancy test can read positive as soon as 11-15 days after conception, 1 day after a missed period. However, more accurate results can be obtained 2 days after a missed period. You will not be able to detect a pregnancy at 1 week after conception if you consider egg fertilization as conception. But you should be able to detect pregnancy within 1 week after the fertilized egg implants in the uterus. How accurate are pregnancy tests? Read on to learn more about home pregnancy tests.
A home pregnancy test detects the presence of human chorionic gonadotropin (hCG), which is produced in a pregnant woman. The fertilized egg takes 5 to 6 days to grow from a single cell into a mass of organized cells (blastocyst), travel to the uterus, and implant. Production of hCG starts only after implantation. Traces of hCG can be seen in urine 3-4 days after the fertilized egg implants in the uterus, and the amount doubles every 48 hours. When there is enough hCG in the body, a pregnancy test can detect it in the urine and produce a positive result.
How soon a pregnancy test will read positive is a variable in women because the time of ovulation, time taken for egg transport, and implantation can vary among individuals. If you have ovulated early in your cycle, a pregnancy test might show up positive even before your next period is due. It gets even more difficult to determine when to take a pregnancy test if your periods are irregular. If your periods are irregular, and your test result is negative, you should repeat a home pregnancy test after 1 week if your cycle doesn’t start, and/or you have pregnancy symptoms.
How accurate are home pregnancy tests?
Home pregnancy tests are quite reliable and usually 99% accurate. However, it is critical to carefully follow the instructions on the package.
- You should test your urine in the morning since hCG levels will be at the highest concentration as soon as you wake up.
- You can take the test at any hour of the day, but you need to keep your bladder full for at least 4 hours before the test.
- Avoid drinking too much water before the test, because it can dilute the hCG levels in your urine.
How to use home pregnancy tests
Here is how home pregnancy tests work:
- The test kits come with a test stick and a container that is used to collect the urine and transfer a few drops to the test stick.
- If you are pregnant and there is sufficient hCG in your urine, the hCG in your urine reacts with the anti-hCG antibodies present in the test stick and inactivates them.
- As anti-hCG bodies are inactivated, the stick indicates a positive pregnancy test.
What can cause a false-positive pregnancy test result?
In rare cases, a false-positive outcome can be caused by:
- Blood or protein in your urine
- Early miscarriage
- Certain medications, such as tranquilizers, anticonvulsants, hypnotics, and fertility drugs
Other reasons for a false-positive result include:
- Molar pregnancy: Also called a hydatidiform mole, a molar pregnancy is a benign growth that develops abnormally after an egg is fertilized. The placenta develops into an aberrant mass of cells and cysts. In rare cases, an embryo develops but is deformed and will not survive. In some cases, no embryo exists at all. Molar pregnancies can have serious complications and must be treated by a specialist.
- Ectopic pregnancy: Ectopic pregnancy occurs when the fertilized egg implants in a location other than the uterus. In a tubal pregnancy, this occurs in, or near, one of the fallopian tubes that connects the ovaries to the uterus. However, the egg can sometimes implant in the abdominal cavity, ovary, or cervix. Because the fertilized egg cannot survive in these locations, the pregnancy cannot progress normally and the growing tissue can harm the mother's internal tissues, resulting in dangerous complications such as life-threatening blood loss. Early treatment of an ectopic pregnancy is critical.
- Chemical pregnancy: Women who get early positive pregnancy test results but then get their period may have a chemical pregnancy. This is a situation in which the fertilized egg implants normally in the uterus, but only long enough to begin generating hCG. The egg then ceases growing for unknown reasons. This form of early miscarriage usually occurs when the fertilized egg has a flaw that prevents it from maturing normally. According to some experts, 20%-30% of all pregnancies end in miscarriage.
What tests are done to confirm pregnancy?
In addition to false-positive results, a home pregnancy test may show a false-negative result, especially if you tested too early or if the kit was defective.
To confirm the results of a home pregnancy test, talk to your doctor to undergo additional tests.
Your doctor may order urine or blood tests, such as the following:
- Urine tests: Urine is tested for the presence of hCG. A diluted sample may produce a false-negative result.
- Blood tests: Blood tests are more sensitive than urine tests and can give an accurate result 9-10 days after conception. Blood test results not only confirm the pregnancy but can also diagnose a potential miscarriage. There are two types.
- Qualitative test: Confirms the presence of the hCG hormone in the blood
- Quantitative test: Measures the amount of hCG present in the blood.
- Higher hCG levels may indicate a multiple or twin pregnancy
- Lower hCG levels may indicate a miscarriage
- A slow rise of hCG levels may indicate an ectopic pregnancy
If pregnancy is confirmed, an abdominal ultrasound can be done to assess the development and health of the fetus.
When should you see a doctor?
Regardless of your pregnancy test results, consult your doctor if you develop any of the following symptoms:
- Dizziness
- Fainting
- Abnormal vaginal bleeding
- Rapid heart rate
- Severe, stabbing pain in the abdomen or on one side of the pelvis
- No period even after multiple negative home pregnancy test results
- Persistent pregnancy symptoms even after negative test results, such as:
- Nausea
- Vomiting in the morning
- Breast tenderness
- Fatigue
If you get a positive pregnancy test with the home pregnancy test kit, you should see your doctor to both confirm the pregnancy and begin prenatal care.
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Frequently asked questions (FAQs) about pregnancy tests
How soon after conception can a pregnancy test read positive?
How soon a pregnancy test will read positive depends on how you define conception. If you consider fertilization of the egg at the moment of conception, it will take about 10 to 11 days before you can get a positive pregnancy test. From the time of implantation, it takes about 3 to 4 days for the human chorionic gonadotropin (hCG) hormone to appear at detectable levels in the urine. The levels double after every 48 hours, so the chances of accurate results get better with time.
You cannot determine when fertilization or implantation takes place inside you, so if you can track your ovulation, it should give you an idea. Eggs live only for 24 hours, so fertilization should take place within that timeframe if it does. Testing at about 11 to 12 days after ovulation is about the earliest you might get a positive pregnancy test, but these may not be reliable. You are more likely to get accurate results if you test after you have missed your period.
Can a pregnancy test read positive before a missed period?
It is possible for a pregnancy test to read positive before a missed period. If you ovulate early in your cycle, say, on the 10th or 12th day, you could test positive by the 22nd or 24th day. If you have a 27-day or 30-day cycle, it will be a few days before your period is due.
How accurate are early pregnancy tests?
You are likely to get the most accurate results if you take your pregnancy test after you miss your period. Most home pregnancy test kit manufacturers claim 99% accuracy, provided you follow the instructions carefully. Taking your pregnancy test earlier than that could give you a false negative or false positive result.
What is the earliest you can take a pregnancy test?
Approximately 11 to 12 days after ovulation is the earliest you can take a pregnancy test and expect a possible positive result. However, it will be more accurate if you take the test as soon as you miss your period.
Can a pregnancy test read positive at 1 week?
A pregnancy test cannot read positive at 1 week. Even though doctors calculate pregnancy from the start of a cycle, in the first two weeks, you are not pregnant. You would ovulate 14 days before your next period, so conception time would fall somewhere in the middle of your cycle. Pregnancy hormone hCG will be detectable in the urine in about 10 to 12 days after ovulation, so the earliest your pregnancy test can read positive is in the 4th week of your cycle.
What factors affect how soon a pregnancy test can read positive?
Many factors about the reproductive cycle are variable between individuals. Assuming that you follow the test kit instructions with care, and the kit is not defective, the factors that affect how soon a pregnancy test can read positive are:
- The length of your cycle
- Time of ovulation
- The time it takes for the fertilized egg to travel from the tube to the uterus and implant
Can a blood test detect pregnancy earlier than a urine test?
Yes, a blood test can detect pregnancy earlier than a urine test, because blood tests are more sensitive and can detect lower levels of hCG than a urine test. A blood test can detect pregnancy in 7 to 10 days after conception, compared to the 11 to 12 days required for hCG to be detectable in the urine.
Are there any signs that indicate a pregnancy test will read positive soon?
A missed period would be the most obvious sign that you are likely to be pregnant. Other early symptoms of pregnancy are breast tenderness, tiredness, morning sickness, and increased urinary frequency. Less frequent symptoms during early pregnancy include spotting, metallic taste in the mouth, food cravings or aversions, bloating, mood swings, cramping, and a few other symptoms.
Medically Reviewed on 9/24/2024
References
Image Source: iStock Images
American Pregnancy Association. What is HCG?
https://americanpregnancy.org/getting-pregnant/hcg-levels/
Betz D, Fane K. Human Chorionic Gonadotropin. [Updated 2021 Aug 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022.
https://www.ncbi.nlm.nih.gov/books/NBK532950
Memon N. How Soon Will a Pregnancy Test Read Positive? MedicineNet.
https://www.medicinenet.com/how_soon_will_a_pregnancy_test_read_positive/article.htm